Visitors to the Tanks are often surprised by the words on a plaque near the Coghlan Tank: “Regarding the original construction of which nothing is accurately known…” There is indeed little hard evidence and there are few reliable sources of information about the Tanks. One favored hypothesis is that Himyar, a pre-Islamic Arabian kingdom that ruled parts of Yemen from 115 B.C. to 525 A.D., started to build water tanks in the area that eventually became the Cisterns of Tawila. The Himyarites are known to have employed water-catchment tanks in other areas under their rule. \

By the time of the British occupation  (beginning in 1839), the Tanks had been almost completely buried by debris carried down the mountains by successive floods. Sir Robert L. Playfair rediscovered the tanks and recognized their potential value. The area had no fresh water and was often cut off from mainland water supplies by hostile tribes. Playfair hoped that the Tanks, once repaired, could provide a reliable source of water for public consumption. The British accordingly set out to restore the tanks to their original function. However, in the process, the British modified the design and layout of the Tanks significantly from their original state. With the intention of storing the greatest quantity of water possible